1. Field of the Invention
The present invention relates generally to a keratome and method of cutting corneal tissue and more particularly to a keratome and method of intraoperatively controlling an operating parameter of the keratome to improve cutting of the corneal tissue.
2. Background
Corneal refractive surgery utilizes an instrument commonly known as a keratome for producing full or partial sections on both the anterior surface of the cornea and within the stromal structure when exposed by a superficial section. The keratome is a mechanical device for performing lamellar resections. The refractive procedures performed with the conventional keratome include AK, ALK, and LASIK. Keratome instruments are available with manual operation, in which case only blade oscillation is motor driven and the cutting head of the instrument is traversed across the corneal surface by the surgeon""s hand. The keratome is also available with more automatic operation. The automatic keratome incorporates a drive mechanism that, in addition to providing blade oscillation, provides transverse movement of the cutting head across the corneal surface.
While the state-of-the art for keratomes has produced instruments with improved clinical performance, none of the currently available keratome instruments, or the improvements incorporated therein, have addressed improving intraoperative performance and results by monitoring one, or more, of the factors influencing clinical outcomes. These factors can include changes in intraoccular pressure which alter tissue stiffness and forces on the blade, the pressure applied by the eyeball holding ring on the corneal surface, speed and uniformity of translation of the keratome""s cutting head, keratome blade oscillation speed, tissue compression, blade motion outside of a defined envelope, blade slowdown, motion in mechanical structure that alters blade position, travel velocity which alters the fluid dynamics of the tissue moving past the blade and across the cutter surfaces, and other factors related to forces applied to the cornea during the cutting cycle.
Accordingly, there is a need to control operating parameters of an automated keratome based on measuring operative factors during the procedure.
An object of the invention is to fulfill the need referred to above. In accordance with the principles of the present invention, this objective is achieved by providing a keratome including a head assembly having a cutting head and blade for cutting corneal tissue and an applanation member associated with the cutting head. The keratome includes an eyeball retaining structure and at least one sensor is associated with the keratome providing measurement of a respective at least one operative factor during cutting of the corneal tissue.
In accordance with another aspect of the invention, a method of controlling cutting of corneal tissue with a blade of a keratome during operation includes measuring an operative factor of a keratome during operation of the keratome, and controlling in real time a movement of the blade based on the measured operative factor.